Electromagnetic injector with assist

ABSTRACT

An electromagnetic injector using a fluid pressure assist to obtain a controlled opening movement of the injector and a rapid closing.

ilite rates atent 1 1 3,839,943 Uinniewsiri Oct. 8, 1974 ELECTROMAGNETICllNJECTOR WITH [58] Field of Search 123/139 E; 91/454; ASSIST 137/6121[75] inventor: .incek lUi'nalewski, Marly-le-Roi,

France [56] References Cited [73] Assignee: Societe Des ProcedesModernes UNITED STATES PATENTS Dlnjection Sopromi, Clichy, France3.753.426 8/1973 Lilley 123/139 E 22 F 7 1 June 19 3 PrimaryExaminerEdgar W. Geoghegan pp 71,716 Assistant Examiner-William F. WoodsAttorney, Agent, or Firm--Darby & Darby [30] Foreign ApplicationPriority Data June 23, 1972 France 72.22729 ABSTRACT An electromagneticinjector using a fluid pressure as- Cl- 91/454, 123/139 E, 137/6121 sistto obtain a controlled opening movement of the [51] lint. 1. F151: 11/08injector and a rapid closing.

2 10 Claims, 1 Drawing Figure HP 79 :77 78 26 i i ix 72 I 13 35 9ELECTROMAGNETIC INJECTOR WITH ASSIST The invention relates to anelectro-magnetic injector with an assist to aid its switching operation.

BACKGROUND OF PRIOR ART In fuel injectors for internal combustionengines, and also in electromagnetically controlled injectors, it isdesired to obtain a relatively slow rise of the injector needle, and avery quick and positive closing of the needle.

It is known to slow the opening movement of the injector needle by meansof a damper consisting of a piston sliding in a fluid filled cylinder,and compressing the fluid during the opening movement of the needle. Thefluid flows out through a reduced orifice so that the pressure in thecylinder acting on the piston slows the opening movement of the needle.

It is also known to control the movements of the injector needle by thepressure existing in a control, or counterpressure, chamber so that adrop in this pressure causes the opening of the needle by unbalancingthe forces acting upon it. The chamber is repressurized to close theneedle. The discharge and the repressurizing of the chamber are assuredeither by a electrically operated valve controlling the chambersdischarge orifice, or by an electrically operated valve controlling boththe discharge orifice and a supply orifice to the control chamber.

In order for the closing movement of the needle to be quick andpositive, it is necessary that the dampers used during needle opening bemade inoperative during the closing phase. One of the means used forthis purpose consists of a mechanical linkage between the damping pistonand the needle, which transmits only forces of compression. The pistonthen returns slowly to its initial position during the time separatingtwo injections. This arrangement does not permit, simultaneously, greatefficiency of the damper and a very high frequency operation of the fuelinjector.

Another solution to the problem resides in filling the cylinder of thedamper through a non-return, or check, valve consisting of a ball and aspring. But when the damper cylinder is of a substantial capacity, as isdesired for good operation a quick closing of the needle allows a verylarge flow to go through the non-return valve, which can lead tomechanical difficulties for the ball and the spring.

The supply of the control cavity by a high pressure fluid through asmall orifice and the discharge through an orifice controlled by anelectrically operated valve do not permit a sufficient discharge and asufficiently rapid repressurizing. And when the injection is of longduration, the consumption of the high pressure fluid is considerable. I

In the case of known devices wherein both orifices, exhaust and supply,are controlled by an electrically operated valve, the operation is suchthat at the instant of switching, i.e. the moment when the supplyorifice must close and the exhaust orifice must open, there is a periodof time during which both orifices are partially open. This allows thehigh-pressure fluid to flow through both orifices. This results in aneedless and large consumption of the high-pressure fluid underpressure.

SUMMARY OF INVENTION In order to avoid the drawbacks of known devices,the goal of the invention is the creation of an injector in which theopening movement of the injector needle is slowed in a controlledmanner, the closing of the needle is extremely quick and the risk ofreopening the injector outlet because of needle bounce is eliminated.

The subject invention relates to an assisted electromagnetic injectorfor internal combusiton engines, of the type in which a pressure drop ina cavity permits the lifting of the injector needle and areestablishment of pressure in said cavity causes the downward return ofthe needle. The injector also utilizes the electromagnetic control of anarmature which assures the opening and closing of a valve controllingthe high pressure sup ply and the closing and opening, respectively, ofan exhaust piping. The injector of the invention includes a firstchamber under high pressure and a second chamber separated from thefirst one by the seat of the valve. A connecting passage system isprovided between a second chamber and a cavity which controls theinjector needle. A passage having a restriction connects the passagesystem to a cylindrical cavity which is to be connected to an exhaustpassage. A free piston provides the seal between the second chamber andsaid cylindrical cavity so that upon opening of the valve, the cavitycontrolling the needle is discharged through the restriction, thuscausing a gradual lifting of the injector needle, and that upon closingof the valve, the cavity controlling the needle is repressurized throughthe passage system, thus causing a quick downward return of the injectorneedle.

DESCRIPTION OF DRAWING An example of execution of the invention isrepresented in the single FIGURE of the attached drawing in which onesees a partial longitudinal section of the control device of theinjector.

DETAILED DESCRIPTION Referring to the drawing, it can be seen that theho]- low housing 1 of the injector has, at its upper part, theelectrical connections 2 for the electromagnetic control winding, and atits lower part: the atomizing jet 3. The control winding is on a body 4in the central bore of the main body 1. The winding controls themovements of a movable armature 5 which carries a hollow tubular part 6whose lower end is chamfered so as to form an active sealing edge 7bearing on a flat surface 8 of a plug or core 9 fastened in the lowerpart of housing ll.

It is at the level of this core 9 that the control device for theinjector needle is essentially situated. The upper part of this needle,or of its control rod, is represented by numeral 10.

A supply of a high pressure control fluid, for example, another suitablegas, is applied through a tubing 11 and the return to low pressure isthrough tubing 12. Both tubings 11 and 12 communicate with passages inthe upper part of the injector body. A first passage system l3, l4, 15,16 is connected to the low pressure return 12 and is always at lowpressure. A large annular chamber 17 in the body and passage 18,communicating with the high pressure supply 11, are always under highpressure during the normal operation of the injector.

The tubular part 6 is rigidly connected to the armature 5. It has afirst internal chamber 19, to which communication is made by a hole 26to a first annular chamber 21 formed in the injector body. The highpressure supply passage 18 opens into annular chamber 21. Tube 6 is alsoformed with a second chamber 22 having a hole 23 through whichcommunication is made to a second annular chamber 24 in the body. Athird annular chamber 25 surrounds the flat surface 8 against whichbears the sealing edge 7 of tube 6. The low pressure passage opens intochamber 25. A valve seat 26 is provided in tubular part 6 between thetwo chamber 19 and 22 for the chamfered end of a piston 27. Piston 27 ismounted in a sealed but sliding manner in the upper part of tube 6 andit normally bears against the body 4 carrying the control winding due tothe high pressure in chamber 21 and 19. However, in the absence of highpressure in the chamber 19, the piston 27 is pushed against the valveseat 26 by a spring 28 set in a cavity of the body 4.

A free piston 29 is located in the lower part of the tube 6, below thevalve seat 26, in a sealed but sliding manner. The lower end of freepiston 29 has a reduced diameter which fits into a cylindrical cavity34) in the core 9. This free piston 29 essentially serves to provide aseal between the chamber 22 of the tube 6 and the cylindrical cavity 30.The purpose of the reduced diameter extension at the lower end of thefree piston 29 is to reduce the volume of fluid inside the tube 6, i.e.,the volume of fluid undergoing the changes in pressure during theoperation of the injector.

The second annular chamber 24 is connected through a passage 31 to aconical chamber 32 in which is located a control needle 33, whoseposition is adjustable from the outside of housing l, for controlling arestricted passage 37. Up stream of the restriction 37, the conicalchamber 32 is connected through a passage 34 to a cavity 35 surroundingthe upper part of the injector needle or of its control rod. Downstreamof the restriction 37 a passage 36 connects the conical chamber 32 tothe cylindrical cavity 30.

The fastening means of the different parts of the injector and the fluidsealing joints are provided in the usual manner.

The operation of the injector is analyzed in the following manner,assuming initially that the high pressure control fluid is not yetsupplied (motor stopped) to inlet 11. In the absence of the highpressure control fluid the spring 23 presses the piston 27 against thevalve seat 26. This holds the tube 6 and the armature 5 in the lowerposition, to close off the high pressure chamber 19 thus preventing anyflow of control fluid. A buildup of the high pressure fluid in chamber19 acts on the piston 27 to push it upwardly and it remains against thebody 4 as long as the high pressure is maintained. The high pressurefluid quickly passes into the second chamber 22 in tube 6 and from therethrough hole 23 into the second annular chamber 24. From chamber 24 itgoes through passage 31 to the conical chamber 32, the passage 34 andinto the cavity 35. The high pressure fluid encounters a delay due tothe narrowing 37 as it goes through the passage 36 into the cavity 31Since the inside diameter of the tube 6 is greater at the level of thepiston 27 (chamber 19) than at the level of the piston 29 (cavity 30)the tube is maintained in the lower position and the sealing edge 7continues to bear against the surface 8 of the core 9. Due to the highpressure in the cavity 35, the needle 10 of the injector is closed. Fora more complete explanation of the movement of needle 10, reference ismade to US. Pat. No. 3,464,627 which is assigned to the assignee of thesubject application.

When an electrical control signal is received by the winding situated inbody 4, the armature 5 is lifted. This lifts the tube 6. The pressure atthe level of the sealing edge 7 begins a discharge towards the lowpressure passage 14 to tubing 12.

The valve seat 26 in the tube 6 then bears against the lower end ofpiston 27, interrupting the circulation of high pressure fluid withintube 6 below chamber 19. The chambers 22, 32 and 35 then dischargethrough the restriction 37. This discharge is therefore gradual, as wellas the rise of injector needle whose upper part 10 rises gradually.

At the end of the control signal the armature 5 and the tube 6 drop onceagain. The high pressure is applied suddenly to the cavity 35 throughthe direct connection 31, 32, 34, which causes the sudden closing of theinjector needle 10.

Thus, in the injector according to the invention, the opening andclosing of the injector needle 10 is controlled by the discharge and thepressurizing of the cavity 35. The opening movement of the injectorneedle 10 is slowed in controlled manner by the position of the controlneedle 33 in the restriction 37. The closing of the injector needle 10is sudden and any risk of reopening because of needle bounce iseliminated. The volume of fluid undergoing the changes of pressure isvery small owing to the presence of the free piston 29 which, inaddition, assures the separation between the second chamber 22 and thecavity 30 situated downstream of the restriction 37. Owing to thisarrangement the free piston is practically always driven back to thebottom of the cavity 30. Finally the restriction 37 partially closes offthe connection which might temporarily exist between the source of highpressure and of low pressure during the switchovers.

What is claimed is:

1. An electromagnetic injector comprising a body formed with a firstcavity (35), an injector needle (10) having a portion mounted in saidbody in fluid communication with said first cavity to move in a firstdirection in response to a pressure drop in said first cavity and in asecond direction opposite said first direction in response to theresumption of pressure in said first cavity, electromagneticallycontrolled armature means (5), inlet means (11) for applying highpressure fluid to the body and means (12) on the body providing a lowpressure return, a bore formed in said body, a tubular member (6)located in said bore and attached to said armature means for movementtherewith, valve means (27) movable within said tubular member, a firstchamber (19) and a second chamber (22) formed in said tubular member anda seat (26) formed on said tubular member between said first and secondchambers for said valve means (27 means (18, 20) providing communicationbetween said high pressure inlet means and said first chamber, firstmeans (31-34) for providing fluid flow communication between said secondchamber (22) of said tubular member and said first cavity (35), a secondcavity (30) formed in said body, means (31, 32, 36) providing fluid flowcommunication between said second chamber (22) of said tubular memberand said second cavity, second means (25, 14) providing communicationbetween said second cavity (30) and said low pressure return (12), thirdmeans (36) having flow restriction means (37) therein for providingcommunication between said first and said second means, a free piston(29) movable within said tubular member (6) to form a seal between saidsecond chamber (22) and said second cavity (30), means engaging saidvalve and acting in the absence of the high pressure for holding thevalve (27) against said seat (26) to block communication between saidfirst and second chambers (19,22) and to hold said tubular member in aposition to seal off communication between said third and said secondmeans, means on said valve responsive to the application of highpressure to said first chamber 19) to move said valve (27 out of saidsealing relationship with said seat to provide communication for thehigh pressure fluid from said first to said second chamber (22) and thenthrough said second means (31-34) to said first cavity (35) topressurize the cavity (35) and to move the injector needle in saidsecond direction, said armature means (5) being responsive to theapplication of a control signal to move said tubular part in a firstdirection out of the sealing relationship between said second cavity(30) and said second means (25,14) to provide a discharge path which isgradual in time from said first cavity to said low pressure returnthrough said third means (36) including the restriction (37) and saidsecond means to cause said needle to move in said first direction, themovement of said tubular part in said first direction by said armaturemeans in response to said control signal also restoring the sealingrelationship of said valve between said first and second chambers.

2. An injector as in claim 1 wherein said second means (31-34) includesa chamber (32) containing a needle (33) adjustable from the outside ofthe injector and defining the restriction (37) of the third means (36).

3. An injector as in claim 1 wherein said seat (26) of 40 5. An injectoras in claim 1 wherein the free piston (29) is dimensioned with respectto the interior of the tubular member to reduce the volume of fluiddistributed inside the tubular member between the second chamber (22)and the second cavity (30).

6. In an assisted electromagnetic fuel injector for internal combustionengines, said injector being of the type including a body having acavity therein, first means including valve means for supplying fluidunder pressure to said cavity, second means also including said valvemeans for providing a discharge of the fluid under pressure from saidcavity, an injector needle in fluid communication with said cavity andcontrolled by the pressure therein such that a pressure drop in thecavity permits movement of the needle in a first direction andresumption of pressure in the cavity causes a movement of the needle ina second direction opposite from said first direction, said injectoralso including electromagnetically controlled armature means foroperating said valve means to control the supply of fluid under pressureby said first means to said cavity and the discharge of the fluid fromsaid cavity by said second means, the improvement comprising said firstmeans includes a first fluid supply path and said second means includinga second fluid discharge path having at least a portion separate fromsaid first: path, said armature means operating said valve means tocontrol the communication of said first and said second paths with saidcavity.

7. An injector as in claim 6 wherein said second path includes arestriction means for controlling the discharge of fluid from saidcavity to thereby control the speed of movement of the injector needlein said second direction, and means located outside of the injector foradjusting the amount of restriction provided by said restriction means.

8. An injector as in claim 7 wherein said restriction means is locatedin said second path between said valve means and the cavity.

9. An injector as in claim 6 wherein said valve means includes a tubularmember located in said body, a free piston mounted in a sealed butsliding manner within said tubular member for controlling the openingand closing of said first and second paths.

10. An injector as in claim 9 wherein said free piston is dimensioned toreduce the volume of fluid inside said tubular member.

1. An electromagnetic injector comprising a body formed with a firstcavity (35), an injector needle (10) having a portion mounted in saidbody in fluid communication with said first cavity to move in a firstdirection in response to a pressure drop in said first cavity and in asecond direction opposite said first direction in response to theresumption of pressure in said first cavity, electromagneticallycontrolled armature means (5), inlet means (11) for applying highpressure fluid to the body and means (12) on the body providing a lowpressure return, a bore formed in said body, a tubular member (6)located in said bore and attached to said armature means for movementtherewith, valve means (27) movable within said tubular member, a firstchamber (19) and a second chamber (22) formed in said tubular member anda seat (26) formed on said tubular member between said first and secondchambers for said valve means (27), means (18, 20) providingcommunication between said high pressure inlet means and said firstchamber, first means (31-34) for providing fluid flow communicationbetween said second chamber (22) of said tubular member and said firstcavity (35), a second cavity (30) formed in said body, means (31, 32,36) providing fluid flow communication between said second chamber (22)of said tubular member and said second cavity, second means (25, 14)providing communication between said second cavity (30) and said lowpressure return (12), third means (36) having flow restriction means(37) therein for providing communication between said first and saidsecond means, a free piston (29) movable within said tubular member (6)to form a seal between said second chamber (22) and said second cavity(30), means engaging said valve and acting in the absence of the highpressure for holding the valve (27) against said seat (26) to blockcommunication between said first and second chambers (19,22) and to holdsaid tubular member in a position to seal off communication between saidthird and said second means, means on said valve responsive to theapplication of high pressure to said first chamber (19) to move saidvalve (27) out of said sealing relationship with said seat to providecommunication for the high pressure fluid from said first to said secondchamber (22) and then through said second means (31-34) to said firstcavity (35) to pressurize the cavity (35) and to move the injectorneedle (10) in said second direction, said armature means (5) beingresponsive to the application of a control signal to move said tubularpart in a first direction out of the sealing relationship between saidsecond cavity (30) and said second means (25,14) to provide a dischargepath which is gradual in time from said first cavity to said lowpressure return through said third means (36) including the restriction(37) and said second means to cause said needle to move in said firstdirection, the movement of said tubular part in said first direction bysaid armature means in response to said control signal also restoringthe sealing relationship of said valve between said first and secondchambers.
 2. An injector as in claim 1 wherein said second means (31-34)includes a chamber (32) containing a needle (33) adjustable from theoutside of the injector and defining the restriction (37) of the thirdmeans (36).
 3. An injector as in claim 1 wherein said seat (26) of saidtubular member (6) for said valve (27) is internal of said tubularmember.
 4. An injector as in claim 1 wherein the end of the tubularmember (6) is chamfered to form a sealing edge (7), a seat (8) formed ona portion of the valve body opposite said sealing edge (27), said edge(7) and said seat (8) forming a seal between said second cavity (30) andsaid second means (25,14) when said valve (27) is open.
 5. An injectoras in claim 1 wherein the free piston (29) is dimensioned with respectto the interior of the tubular member to reduce the volume of fluiddistributed inside the tubular member between the second chamber (22)and the second cavity (30).
 6. In an assisted electromagnetic fuelinjector for internal combustion engines, said injector being of thetype including a body having a cavity therein, first means includingvalve means for supplying fluid under pressure to said cavity, secondmeans also including said valve means for providing a discharge of thefluid under pressure from said cavity, an injector needle in fluidcommunication with said cavity and controlled by the pressure thereinsuch that a pressure drop in the cavity permits movement of the needlein a first direction and resumption of pressure in the cavity causes amovement of the needle in a second direction opposite from said firstdirection, said injector also including electromagnetically controlledarmature means for operating said valve means to control the supply offluid under pressure by said first means to said cavity and thedischarge of the fluid from said cavity by said second means, theimprovement comprising said first means includes a first fluid supplypath and said second means including a second fluid discharge pathhaving at least a portion separate from said first path, said armaturemeans operating said valve means to control the communication of saidfirst and said second paths with said cavity.
 7. An injector as in claim6 wherein said second path includes a restriction means for controllingthe discharge of fluid from said cavity to thereby control the speed ofmovement of the injector needle in said second direction, and meanslocated outside of the injector for adjusting the amount of restrictionprovided by said restriction means.
 8. An injector as in claim 7 whereinsaid restriction means is located in said second path between said valvemeans and the cavity.
 9. An injector as in claim 6 wherein said valvemeans includes a tubular member located in said body, a free pistonmounted in a sealed but sliding manner within said tubular member forcontrolling the opening and closing of said first and second paths. 10.An injector as in claim 9 wherein said free piston is dimensioned toreduce the volume of fluid inside said tubular member.